Q. 111. During respiration, exchange of Oxygen and Carbon dioxide takes in:
(A) Pharynx
(B) Trachea
(C) Alveoli
(D) Larynx
Answer:
(C) Alveoli
Explanation:
In the human respiratory system, the actual exchange of oxygen and carbon dioxide takes place across the thin, specialized walls of the alveoli in the lungs.
Q. 112. Which of the following enzyme gets mixed with food in our mouth?
(A) Trypsin
(B) Amylase
(C) Pepsin
(D) Lipase
Answer:
(B) Amylase
Explanation:
Salivary amylase is secreted by the salivary glands in the mouth, where it mixes with food to begin the breakdown of complex carbohydrates (starches) into simple sugars.
Q. 113. The autotropic mode of nutrition requires:
(A) Carbon dioxide and water
(B) Chlorophyll
(C) Sunlight
(D) All of these
Answer:
(D) All of these
Explanation:
Autotrophic nutrition (photosynthesis in plants) requires carbon dioxide, water, chlorophyll, and sunlight to synthesize food successfully.
Q. 114. When water enters the guard cells the stomata:
(A) opens
(B) closes
(C) either opens or closes
(D) no effect
Answer:
(A) opens
Explanation:
When water flows into the guard cells, they swell and become turgid, which forces the stomatal pore to open.
Q. 115. Involuntary actions including blood pressure, salivation and vomiting are controlled by _____ in the hind brain.
(A) Pons
(B) Medulla
(C) Cerebellum
(D) Cerebrum
Answer:
(B) Medulla
Explanation:
The medulla oblongata, located in the hindbrain, regulates vital autonomic (involuntary) functions such as heart rate, blood pressure, salivation, and vomiting.
